This invention relates to a coupling for connecting pipes provided with exterior connection grooves. More particularly, the invention is concerned with a means, in the form of a plug-like removable insert, for converting a coupling which normally flexibly connects the pipe ends together and permits limited movement of the connected pipes, into a rigid, nonmovable connection.
Conventional couplings used to connect the ends of pipes having exterior connection grooves generally are formed of a circular casing made of two semi-circular segments which are connected together to encircle the pipes. Typically, the segments, are U-shaped in cross-section, with their legs extending radially inwardly. Thus, the free ends of the legs form keys or tenons which extend within grooves formed in the exterior surfaces of the pipes.
Usually, a rubber-like gasket is arranged around the adjacent pipe ends and the two segments are positioned around the gasket, with their keys or tenons, that is, the free ends of their legs, enclosing the gasket. At that point, the segments are connected together to encircle the joint.
Such couplings are somewhat flexible, in that they provide some permissible relative movement between the pipe ends and between the pipes and the coupling because the keys or free edges of the legs of the segments are usually narrower than the grooves in the pipes. That is, there is some permissible movement between the keys and the pipe grooves. This is particularly useful in plumbing systems where pipes may be somewhat misaligned during installation or may become misaligned or may expand or contract due to ambient conditions or to the temperature of the fluid flowing through the pipes.
However, in some installations it is necessary to have a rigid coupling where the pipe ends are held against relative movement with respect to each other or with respect to the coupling. In such cases, a typical coupling of the type described above is not adequate to hold the pipes against relative movement. Hence, different couplings are used to produce a rigid connection. One example of this type of rigid coupling construction is disclosed in U.S. Pat. No. 4,639,020 issued Jan. 27, 1967. In that patent, the coupling segments are provided with overlapping side lugs through which bolts are extended, for bolting the segments together. The adjacent surfaces of the two segments, at the bolt lugs, are angled in two directions, that is, in an axial and in a radial direction. Thus, as the bolts are tightened, the two segments are offset relative to each other to lock into the pipes. This is illustrated, particularly, in FIG. 10 of the above U.S. Pat. No. 4,659,020.
Where it is necessary to use couplings which provide a rigid connection between the adjacent pipe ends, it is necessary to inventory and to have such couplings available on a job site along with the usual couplings which provide the flexible connections. Thus, it is necessary to manufacture a separate line of couplings in assorted sizes, which produce rigid connections for use as necessary.
In order to obviate this need for additional couplings, it is desirable to have couplings which function to produce either a flexible coupling connection or, alternatively, a rigid connection, as desired. This invention is concerned with providing a means for selectively converting a standard, flexible type coupling, into a rigid coupling by means of a special connector insert part.